1. Technical Field of the Invention
The present invention is directed to Distributed Antenna Systems (DASs) and more particularly, to methods and systems for supporting multiple wireless data services on a DAS.
Distributed Antenna Systems are used to provide or enhance coverage for wireless services such as Public Safety, Cellular Telephony, Wireless LAN and Medical Telemetry inside buildings and over campuses. The general architecture of a DAS is depicted in FIG. 1.
A single DAS can serve a single wireless service or a combination of many wireless services operating over multiple bands. With respect to each wireless service served by the DAS, the Aggregation Configuration of the wireless service can be characterized as non-aggregated or aggregated. In a non-aggregated configuration, there is a 1:1 relationship between DAS antennae and Base Transceiver Stations (BTS) or Transmitter/Receiver units for that wireless service. In an aggregated configuration, each BTS unit for a given wireless service is associated with multiple DAS antennae through a hierarchy of aggregation. For example, in FIG. 2, Services A, B, and C are aggregated and Services D1, D2, and D3 are non-aggregated. Services such as D1, D2, and D3 can be aggregated as well. The ability to aggregate services is typically a function of the remote wiring closet equip. Typically, wireless LAN services are arranged in a non-aggregated configuration when using a DAS while cellular services are typically arranged in an aggregated configuration.
One desired characteristic of a multi-service DAS is that it can use a single antenna to radiate and receive the signals for all services and frequency bands supported by the DAS. Such an antenna would need to cover (i.e. have acceptable performance) in all frequency bands of interest and is commonly referred to as a Broadband Antenna. An example of a supported frequency range for a DAS antenna would be 400 MHz-6 GHz. To provide MIMO based services, a MIMO antenna which includes multiple antenna elements at a common location can be used.
In referring to the signal flows in DAS systems, the term Downlink signal refers to the signal being transmitted by the source transmitter (e.g. cellular base station) through an antenna to the terminals and the term Uplink signal refers to the signals being transmitted by the terminals which are received by an antenna and flow to the source receiver. Many wireless services have both an uplink and a downlink, but some have only a downlink (e.g. a mobile video broadcast service) or only an uplink (e.g. certain types of medical telemetry).
2. Description of the Prior Art
In addition to providing cellular and other wireless services, these DAS can be used to provide Time Division Duplexed (TDD) based services such as WiFi (IEEE 802.11 and similar standards), ZigBee, Blue Tooth, WiMAX, Advanced Wireless Services (AWS) as well as Frequency Division Duplex (FDD) based services such as WiMAX, Personal Communication Services (PCS) and AWS. When a DAS used to provide these services, either the Main wiring closet or remote wiring closet equipment needs an interface to connect the service network to the DAS. These source interfaces are commonly referred to as a Macro/Micro/Pico/Femto BTS or Access Point (AP) etc. For each additional wireless service that is connected to the DAS a separate, dedicated BTS is needed. Thus, it is difficult to support multiple service networks on a DAS because many expensive BTS devices are needed.